After a bit of a problem with the super-elevation on my module at the Broadclyst meeting yesterday, I was trying to figure out how to measure it.
I then remembered I had an app on my iPod to measure gradients. https://itunes.apple.com/gb/artist/kevi ... d305581830
Placing the iPod on the track was OK but no good for moving along the track. I have some accurate square steel blocks (I made them during my apprenticeship, never saw the point, but they are great for structure building!) one of those helped. Then I put it on a flat car, but I found a car rocks too much.
Finally I decided to make a measuring car. I made a plastic mount for the iPod mounted on a truck, This still rocked a bit so added some pads to the underside so it ran on the axles instead of the axle boxes.

A bolt through the plastic layers and truck hold it all together

The app measures gradient % and degrees, degrees are how super elevation or cant is usually measured.

The top layer can turn so it can also measure the gradient.

I can now push the car slowly along the track and see how much cant I have.

I should add that the bit of bent metal in two photos is my favourite track reworking tool. It is bent from a bit of nickelsilver plate. The plain end is used to lever track up from alongside a spike or pin, preventing the rail being ripped off the ties, and was very useful for this levelling job after cutting through the ballast. This end was also used to clear out beneath the track and hold the track up while placing cardboard strips under the track.
The other end is tapered and thinned, with a narrow slot, spike shaft width cut in it. This end can get under a spike or pin head and lever it out without damaging track or spike.
Before this I used screw drivers, pliers etc. sound familiar? which often damaged ties.

Like the level car it was built after struggling to do a job, and for a little bit of work gives a tool that makes life easier from now on.

I use the Micro Mark digital level meter (designed I think for machine tool beds) but put it on a long wheelbased flat car with vertically restricted axles.
I find you need to measure gradient (I have some at 2.8% and superelevation over a longish length otherwise in the short lengths the readout varies
too frequently so is hard to appreciate in % terms Ron Gager